Vertical bag form-fill-seal packaging method

ABSTRACT

The present invention provides a first transfer unit instead of a stationary chute. The first drive unit drives the first transfer unit and is controlled to maintain a bag ejection interval or bag posture. Thus, variation of the bag-to-bag pitch and bag posture even in a high-speed operation with an improved bag-forming capacity is prevented.

This is a continuation application of U.S. patent application Ser. No.09/911,621, filed Jul. 25, 2001, which claims the right of priority toJapanese Patent Application No. 2000-232617, filed Aug. 1, 2000.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a vertical bag form-fill-seal packagingmachine, and more particularly to a vertical bag form-fill-sealpackaging machine for forming bags by sealing a continuous tubularpackaging material in which a product to be packaged is filled, and thenseparating and ejecting each of the bags.

2. Background Information

Vertical bag form-fill-seal packaging machines exist as packagingdevices that fill a product to be packaged, such as food, into bagswhich are being formed at the same time. In a conventional vertical bagform-fill-seal packaging machine, a packaging material in a sheet-likefilm form is fed over a former and into a tube. The material is formedinto a tubular shape that conforms to the vertically long tube throughwhich it goes. The overlapped vertical ends of the tubular packagingmaterial are then sealed (heat-sealed) by a vertical sealing mechanism.The product to be packaged, which is allowed to drop from a higherposition, is filled into the tubular packaging material via the tube.Then, the portion of the tubular packaging material that will become thetop of a bag and the bottom of its next bag is transversely sealed by atransverse sealing mechanism provided under the tube. Immediately afterthis, a cutter cuts the center of the transversely sealed portion. Insuch a vertical bag form-fill-seal packaging machine, two types ofoperations, the forming of the bags and the filling of the product to bepackaged into the bags, are carried out continuously as described above.

In such a conventional vertical bag form-fill-seal packaging machine,each of the bags separated from the following bag by the cutter fallsfreely onto a stationary chute provided below the transverse sealingmechanism, and is led to a belt conveyor in a downstream process. Thestationary chute is similar to a playground slide made of a metal plateor the like, and plays the role of transferring the bag to the beltconveyor in the downstream process by taking advantage of gravity.

In a conventional vertical bag form-fill-seal packaging machine, thebags are allowed to fall freely using gravity before they are ejectedonto the belt conveyer in the downstream process. With improvements inbag-forming capacity in recent years, however, the quantity of the bagsejected per unit of time has increased. With the traditional quantitiesof bags to be ejected, a small degree of variation in the bag ejectioninterval and posture would not lead to a problem on the belt conveyor orother devices in the downstream process. However, with the quantity ofthe bags to be ejected ever increasing, a problem with the devices couldresult in the downstream process. Particularly, with the increase in thequantity of the bags to be ejected, or the higher-speed operation of thevertical bag form-fill-seal packaging machine, which causes the bags tobe ejected at a shorter interval, a minor variation in the bag ejectionintervals may lead to a problem with the devices in the downstreamprocess. For example, two bags may be loaded instead of one on a weightchecker or a seal checker in the downstream process, or the mishandlingof the bags or the disorganization of the file or files of the bags mayresult at a boxing device. Such problems could stop the production line,thus lowering the line operation rate and preventing the achievement ofhigh-speed operation.

In view of the above, there exists a need for a vertical bagform-fill-seal packaging machine which overcomes the above mentionedproblems in the prior art. This invention addresses this need in theprior art as well as other needs, which will become apparent to thoseskilled in the art from this disclosure.

SUMMARY OF THE INVENTION

A principal object of the present invention is to provide a vertical bagform-fill-seal packaging machine that prevents variation in the pitchand posture of the bags that are continuously ejected.

A vertical bag form-fill-seal packaging machine in accordance with afirst aspect of the present invention provides a vertical bagform-fill-seal packaging machine for forming bags by sealing acontinuous tubular packaging material in which a product to be packagedis filled, and then separating and ejecting each of the bags. Thevertical bag form-fill-seal packaging machine includes a first transferunit, a first drive unit, and a control unit. The first transfer unittransfers the separated bags to another transfer unit or conveyorprovided in a downstream process. The first drive unit drives the firsttransfer unit. The control unit controls the first drive unit to controlthe interval or the posture of the bags to be ejected after beingtransferred by the first transfer unit. In this case, the first transferunit is provided instead of a conventional stationary chute. The baginterval and the posture of the bags to be ejected are maintained bycontrolling the first drive unit that drives the first transfer unit.Therefore, even during high-speed operation with an improved bag-formingcapacity, the variation in the pitch and the posture of the bags can bereduced. With a conventional stationary chute, on which frictionalresistance (as the bag slides) and an impact (as the bag comes off thechute) occurs, there is a high probability that the pitch and theposture of the bags may be adversely affected. By using the packagingmachine as defined in the first aspect of the present invention, inwhich the first transfer unit is provided and the transfer of the bag onthe first transfer unit is controlled, variations in the bag ejectionpitch and posture are prevented.

A vertical bag form-fill-seal packaging machine in accordance with asecond aspect of the present invention is the machine as defined in thefirst aspect, wherein the control unit provides control so that the bagejection interval is larger than the bag separation interval. The bagsare prevented from being transferred to the conveyor or the transferunit or other devices in the downstream process without a properinterval.

A vertical bag form-fill-seal packaging machine in accordance with athird aspect of the present invention is the machine as defined ineither of the previous aspects, wherein the first transfer unit is abelt.

In this aspect, a relatively simple structure having a belt and a firstdrive unit for moving the belt, such as a motor, is used to restrictvariation in the bag ejection pitch and posture. It is easy andinexpensive to incorporate this structure into a vertical bagform-fill-seal packaging machine of the present invention or duringinitial construction to retrofit it to a conventional vertical bagform-fill-seal packaging machine. To prevent variation in bag posturethat may be caused by the drop impact, the belt is preferably set in aposition so that it contacts the bags immediately after they areseparated from the supply roll of packaging material.

A vertical bag form-fill-seal packaging machine in accordance with afourth aspect of the present invention is the machine as defined in thethird aspect, wherein the belt is inclined so that the bags movediagonally downward. In this case, with the belt inclined, the bagsseparated from the supply roll of the packing material surely contactthe belt. The incline of the belt is such that it allows the bags tomove diagonally downward, thereby reducing the impact that may be causedon the bags upon their contact with the belt, thus reducing changes inbag posture. Additionally, preventing the bags from being transferred ina stand-up posture, the bag-to-bag interval is more constant. Theincline of the belt further contributes to a reduction in the impactthat may be caused when the bags move from the belt to the transfer unitor conveyor in the downstream process.

A vertical bag form-fill-seal packaging machine in accordance with afifth aspect of the present invention is the machine as defined in thethird or fourth aspect, wherein the first transfer unit includes twobelts holding each of the bags in a sandwiched manner. In this case, thebags are transferred while being held by the two belts in a sandwichedmanner. Thus, the bags are securely held, thereby reducing problematicvariations in the bag ejection pitch that may be caused by the slippageof the bags and belt.

A vertical bag form-fill-seal packaging machine in accordance with asixth aspect of the present invention is the machine as defined in thefifth aspect, wherein the first transfer unit is such that a part of atransfer passage formed between the two belts is inclined so that thedirection of the bag transfer changes as the bag moves therethrough.

A vertical bag form-fill-seal packaging machine in accordance with aseventh aspect of the present invention is the machine as defined in thefifth or sixth aspect, further including a means for changing thedistance between the two belts, wherein the control unit controls themeans for changing the distance between the two belts according to thebags, so as to adjust the distance between the two belts. In this case,by taking advantage of the structure that holds each of the bags withthe two belts in a sandwiched manner, the volume of the gas to be filledinto the bags is optimized. In other words, by adjusting the distancebetween the two belts, the volume of the gas to be filled into theformed bags can be controlled, thus making the volume of the bags to beejected uniform. Generally with the vertical bag form-fill-sealpackaging machine, the gas to be filled is sprayed into the bags at thetime of bag forming. By spraying it with a little more than the requiredamount and making the volume of the bags uniform through the adjustmentof the belt-to-belt distance, the volume of the bags to be ejected willbe substantially uniform even if the pressure of the gas supply unit haschanged.

A vertical bag form-fill-seal packaging machine in accordance with aneighth aspect of the present invention is the machine as defined eitherin the fifth, sixth, or seventh aspects, wherein the sealing isheat-sealing and the machine further includes a cooling unit forspraying a cooling gas on the sealed part of each of the bags held in asandwiched manner by the two belts. In this case, by taking advantage ofthe structure that holds each of the bags in a sandwiched manner, a gasfor cooling is sprayed onto the bags thus held in a sandwiched manner,to ensure the bonding strength of the heat-sealed part. With aconventional machine, there is a high possibility that the posture ofthe bags to be ejected varies if a cooling gas is sprayed. However, withthe two belts sandwiching the bags in the machine of the presentinvention, the posture will rarely be affected even when cooled byspraying a gas. In addition, the cooling strengthens the sealing,thereby reducing the problem of bag breakage that may cause theproduction line to stop while the bags are still being transferred.

A vertical bag form-fill-seal packaging machine in accordance with aninth aspect of the present invention is the machine as defined in thefirst or second aspect, further including a second transfer unit forreceiving, transferring, and ejecting the bags transferred from thefirst unit, and a second drive unit for driving the second transferunit, wherein the control unit further controls the second drive unit inaddition to the first drive unit.

A vertical bag form-fill-seal packaging machine in accordance with tenthaspect of the present invention is the machine as defined in the ninthaspect, wherein the transfer unit is a belt with a guide barapproximately orthogonal to the direction of transfer. In this case, thetransfer unit, which is a belt, has a guide bar that prevents the bagsfrom shifting on the bag.

A vertical bag form-fill-seal packaging machine in accordance with aneleventh aspect of the present invention is the machine as defined inany of the previous aspects, further including a memory storage unit forstoring control settings for each set of products to be packaged,wherein the control unit maintains control according to the settingsstored in the memory storage unit.

A vertical bag form-fill-seal packaging machine in accordance with atwelfth aspect of the present invention is the machine as defined in theeleventh aspect, wherein at least one of the control setting items to bestored in the memory storage unit is the speed of the drive unit. Inthis case, by setting the drive unit speed according to the bags, itbecomes possible to adjust the bag-to-bag pitch to be ejected and thebag ejection time interval to reflect the operating conditions of theequipment in the downstream process.

A vertical bag form-fill-seal packaging machine in accordance with athirteenth aspect of the present invention is the machine as defined inthe twelfth aspect, wherein the control unit provides data at least onthe bag ejection time interval to the external equipment in thedownstream process. In this case, because the data on the time intervalbetween each bag's ejection are provided to the external equipment inthe downstream process, an operation synchronizing with the ejectiontime intervals of the bags sent from the vertical bag form-fill-sealpackaging machine becomes possible.

These and other objects, features, aspects and advantages of the presentinvention will become apparent to those skilled in the art from thefollowing detailed description, which, taken in conjunction with theannexed drawings, discloses a preferred embodiment of the presentinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the attached drawings which form a part of thisoriginal disclosure:

FIG. 1 is a schematic diagrammatical view of a conventional vertical bagform-fill-seal packaging machine with devices in the upstream anddownstream processes;

FIG. 2 is a schematic diagrammatical view illustrating an example of aproduction line for a downstream process for a bag ejected from aconventional vertical bag form-fill-seal packaging machine;

FIG. 3 is a schematic structural diagrammatical view of a conventionalvertical bag form-fill-seal packaging machine;

FIG. 4 is an elevational view of a vertical bag form-fill-seal packagingmachine in accordance with a first embodiment of the present invention;

FIG. 5 is a control block diagrammatical view of the vertical bagform-fill-seal packaging machine of FIG. 4;

FIG. 6 is an elevational view of the adjacent area of the forced ejectorof FIG. 4;

FIG. 7 is an elevational view of the adjacent area of the forced ejectorin accordance with a second embodiment of the present invention;

FIG. 8 is a rear elevational view of the adjacent area of the forcedejector of FIG. 7;

FIG. 9 is an elevational view of the adjacent area of the forced ejectorin a variation of the second embodiment; and

FIG. 10 is an elevational view illustrating how the belt-to-beltdistance of the forced ejector is changed in another variation of thesecond embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment

A conventional measuring and bag forming/packaging line is illustratedin FIG. 1, together with an example of devices in the upstream anddownstream processes. In this case, a product for example, potato chips,is transferred by a supply conveyor 101 to a position above themeasuring unit 110. The product, once in the measuring unit 110, ismeasured into a predetermined weight (or quantity) and continuouslydischarged downward.

The product discharged from the measuring unit 110 moves into a verticalbag form-fill-seal packaging machine 120 located under the measuringunit 110. The vertical bag form-fill-seal packaging machine 120 is adevice for forming bags, and filling and packing a product in the bagssimultaneously. The bags containing the product as a result of thepackaging slide down the stationary chute 129 provided with the verticalbag form-fill-seal packaging machine 120, and are loaded onto thetransfer conveyor 130. The transfer conveyor 130 transfers the bagscontinuously discharged there to a weight checker 140 in the downstreamprocess.

If bags need to be continuously packed in carton boxes, the bags aretransferred from the transfer conveyor 130 to the weight checker 140 anda sealing checker 150 as shown in FIG. 2. The bags subjected to theweight and sealing checks here go through a directing unit 160 and aposture adjustment unit 170 so that they are sent to a boxing unit 180in a file or files.

The boxing unit 180 is provided with a handling mechanism 181 holdingthe bags through suction, to pack the bags B into a carton box. Thecarton box in which the bags B are packed is transferred via a cartonbox transferring unit 190 to a box-sealing unit and a labeling unit (notshown).

FIG. 3 shows the major structure of a conventional vertical bagform-fill-seal packaging machine 120, the so-called vertical pillowpackaging machine. In the vertical bag form-fill-seal packaging machine120, sheet-like film Fm drawn from a roll of film 128 (see FIG. 1) isformed into a tubular shape through a former 121 and a tube 122 and feddownward by a pull-down belt mechanism 125. The overlapped vertical endsof the tubular film Fmc is heat-sealed by a vertical sealing mechanism123. When the measured product fills the tubular film Fmc through thetube 122, the transverse sealing mechanism 124 provided under the tube122 performs transverse sealing in the area that will become the top ofthe bag preceding and the bottom of the following bag. Concurrently withthe transverse sealing, the center of the transversely sealed part iscut by a cutter built in the transverse sealing mechanism 124. The bagsthus cut slide down on the stationary chute 129 provided under thetransverse sealing mechanism 124, and then transferred on a transferconveyor 130 to the devices in the downstream processes.

Overall Structure

A vertical bag form-fill-seal packaging machine in accordance with thefirst embodiment of the present invention is described below.

FIG. 4 shows a vertical bag form-fill-seal packaging machine 1,including a forced ejector 6 in accordance with a first embodiment ofthe present invention. The vertical bag form-fill-seal packaging machine1 is a machine for receiving the film from a supply unit 4 and packing aproduct such as food for example, potato chips into bags, and mainlyincludes a bag-forming/packaging section 5 and a forced ejector 6. Thebag forming/packaging section 5 is a main region for packing the productinto bags. The film supply unit 4 supplies the bag-forming/packagingsection 5 with the film that ultimately becomes bags. The forced ejector6 forcibly ejects downward the bags formed by the bag-forming/packagingsection 5. An operation switch 7 (see FIG. 5) is provided at the frontof the vertical bag form-fill-seal packaging machine 1. A liquid-crystaldisplay 8 for showing the status of the operation is provided where theoperator manipulating the operation switch can visually checkoperations. The control unit 20 shown in FIG. 5 controls the operationof each of the drive units for the vertical bag form-fill-seal packagingmachine 1 and displays various data on the liquid-crystal display 8based on the input from the operation switch 7.

A Structure of the Film Supply Unit

Referring to FIG. 4, the film supply unit 4 supplies sheet-like film toa forming mechanism 13 in the bag-forming/packaging section 5 that is tobe described later. A roll of film is set on the film supply unit 4 sothat the film Fm is unreeled from the roll.

A Structure of the Bag-Forming/Packaging Section

As shown in FIG. 4, the bag-forming/packaging section 5 includes theforming mechanism 13, a pull-down belt mechanism 14, a vertical sealingmechanism 15, and a transverse sealing mechanism 17. The formingmechanism forms the film Fm that is fed in as a sheet into a tubularshape. The pull-down belt mechanism 14 transfers the tubular-shaped film(hereinafter called “tubular film Fmc”) downward. The vertical sealingmechanism 15 vertically seals the overlapped part of the tubular filmFmc. The transverse sealing mechanism 17 transversely seals the tubularfilm Fmc to close the top and bottom of each of the bags.

As shown in FIG. 4, the forming mechanism 13 has a tube 31 and a former32. The tube 31 is a cylindrical member with its top and bottom endsopen. The tube 31 is made integral with the former 32 through a bracket.Measured items such as potato chips are put into the open top end of thetube 31 from the measuring unit 110. The former 32 is provided in such amanner that it surrounds the tube 31. The shape of the former 32 is suchthat allows the sheet-like film Fm fed from the film supply unit 4 to beformed into a tubular shape when it passes between the former 32 and thetube 31. The pull-down belt mechanism 14 is a mechanism for sucking thefilm Fm wound on the tube 31 to pick it up and transfer it downward. Thepull-down belt mechanism 14 mainly includes a driver roller 41 and adriven roller 42, as well as a suction belt 43. The vertical sealingmechanism 15 vertically seals the overlapped part of the film Fm woundon the tube 31 by heating it while pressing it against the tube 31 at apredetermined pressure. The vertical sealing mechanism 15 has a heaterand a heater belt that contacts the overlapped part of the film Fm whenheated by the heater.

The transverse sealing mechanism 17 is provided beneath the formingmechanism 13, the pull-down belt mechanism 14, and the vertical sealingmechanism 15. As shown in FIG. 6, the transverse sealing mechanism 17has a pair of symmetrical sealing jaws. Each of the two sealing jaws 17a turns in the shape of the letter “D”, leaving tracks T that aresymmetrical to each other. The sealing jaws 17 a mate with each otherwhen the tubular film Fmc is ready to be transversely sealed. Thetransverse sealing mechanism 17 has a cutter built therein. The cutterseparates the bag from the tubular film Fmc that follows the bag at thecenter of the part sealed by the sealing jaws 17 a. The transversesealing mechanism 17 crimps the part to be transversely sealed bysandwiching the tubular film Fmc between the sealing jaws 17 a, aprocess that requires heat in addition to pressure. Therefore, in orderto heat the mating surfaces of the sealing jaws 17 a that contact thetubular film Fmc, a heater is provided in the each of the sealing jaws17 a, and a thermocouple is attached thereto as well.

A Structure of the Forced Ejector

The forced ejector 6 mainly includes an endless belt 61, a driver roller62, a driven roller 63, and an AC servo motor 64. The servo motor 64turns the driver roller 62 and provides super-fine turning control. Theservo motor 64 is controlled by the control unit 20 as shown in FIG. 5.As shown in FIG. 6, the belt 61 is inclined so that the bag B movesdiagonally downward. Still referring to FIG. 6, the forced ejector 6 ispositioned at a height that enables the bottom of the bag B to contactwith the upper side of the belt 61 when the bag B is separated by thecutter provided in the sealing jaws 17 a. If the forced ejector 6 is ata position higher than this, the belt 61 will thrust the bag B upwardbefore the transverse sealing is completed, resulting in a poortransverse sealing. Conversely, if the forced ejector 6 is located toolow, the falling distance to the point where the separated bag Bcontacts the belt 61 becomes too long, thus causing the bag B to bounceon the belt 61 and deteriorating the stability of the posture of the bagB.

A Structure of the Control Unit

As shown in FIG. 5, the control unit 20 is connected with the filmsupply unit 4, bag-forming packaging sections 5, and forced ejector 6 ofthe vertical bag form-fill-seal packaging machine 1 to control theoperation of each of the drive units. First, the control unit 20controls the rotating speed of the sealing jaws 17 a of the transversesealing mechanism 17 as well as the traveling speed of belt 61 of theforced ejector 6 according to the downward feeding speed of the tubularfilm Fmc on the pull-down belt mechanism 14. In controlling the forcedejector 6, the rotating speed of the servo motor 64 is controlledaccording to the feeding speed of the tubular film Fmc, i.e. thebag-forming/packaging section 5 bag-forming capacity, to change theejection speed of the bag B (the traveling speed of the belt 61) at theforced ejector 6. In this production line, an AC servo motor 131 isemployed as a driving power source for the transfer conveyor 130. Theservo motor 131 is controlled according to the data on the ejectingspeed of the forced ejector 6 and the bag ejection time interval thatare output from the control unit 20. The controlling of the servo motor64 for the forced ejector 6 and the servo motor 131 for driving thetransfer conveyor 130 may be carried out by changing the rotating speedto adjust the ejection interval between the bags B, or by performing anintermittent driving to repeat ON/OFF switching of operations to adjustthe bags B′ ejection interval.

Further, the control unit 20 has an external output terminal 21, whichcan send the data on the bags B ejecting speed and bag ejection timeinterval to the transfer conveyor 130 and other devices in thedownstream process (the weight checker 140, the sealing checker 150, theboxing unit 180, and the like shown in FIG. 2). In the control unit 20,a memory storage unit such as a hard disc is also provided. Data on theshape, dimensions, material, volume, and the like for each set of thebags are stored in the memory storage unit, and the control patterns foreach of the drive units, including the appropriate controlling patternfor the transfer speed of the forced ejector 6, are preset.

An Operation of the Vertical Bag Form-Fill-Seal Packaging Machine

An operation of the vertical bag form-fill-seal packaging machine 1 isdescribed below.

Referring to FIG. 4, the sheet-like film Fm fed from the film supplyunit 4 to the forming mechanism 13 moves through the former 32 and iswound on the tube 31. The sheet-like film Fm is shaped in a tubular formand transferred, in this condition, downward by being carried on thepull-down belt mechanism 14. When wound on the tube 31, the film Fm hasboth ends overlapped on its circumference. The overlapped part is to bevertically sealed by the vertical sealing mechanism 15. The tubular filmFmc, now in a cylindrical form as a result of the vertical sealing,moves out of the tube 31 and down to the transverse sealing mechanism17. At this point, the position of the tubular film Fmc is in the areaindicated by the double-dot dash line in FIG. 4. Now, concurrently withthe travel of the tubular film Fmc, a mass of items, for example, potatochips, falls from the measuring unit 110 via the tube 31. At thetransverse sealing mechanism 17, the bottom and the top of the bag aretransversely sealed, in sequence, with the potato chips present in thetubular film Fmc. In the process of transverse sealing by the transversesealing mechanism 17, the cutting process by the cutter provided in thesealing jaws 17 a is carried out concurrently as shown in FIG. 6. Thecutter cuts the approximate center of the transversely sealed part.Thus, as seen in FIG. 4, the bag B is separated from the tubular filmFmc that follows, and contacts the upper part of the belt 61 of theforced ejector 6 and is forcibly carried diagonally downward accordingto the turn of the belt 61.

In this process, if the bag B contacts the belt 61 at a speed lower thanthe traveling speed of the belt 61, the bags B may be bridged and tipforward. If the traveling speed of the belt 61 is substantially higherthan the falling speed of the bag B, the belt surface may not be able tocatch the bag B. Therefore, the traveling speed of the belt 61 is setequivalent to or a little higher than the falling speed of the bag B.The maximum value of this speed setting varies with the materials of thebelt 61, the film Fm, and the weight of the filled bag B. Therefore, thecontrol unit 20 considers these conditions in controlling the rotatingspeed of the servo motor 64 to adjust the traveling speed of the belt61.

In setting a specific traveling speed for the belt 61, the distancebetween the transverse sealing mechanism 17 and the belt 61, the fallingspeed of the bag B upon separation, gravitational acceleration, and thelike are used as the bases for calculation.

The vertical bag form-fill-seal packaging machine, in accordance withthe first embodiment of the present invention, has the followingfeatures:

The vertical bag form-fill-seal packaging machine 1 is provided with theforced ejector 6 instead of a conventional stationary chute 129 as seenin FIG. 3. Thus, variation of the ejection pitch and the postures of thebag B ejected onto the transfer conveyor 130 is prevented. With aconventional stationary chute, on which frictional resistance is appliedwhen the bag B slides down or the impact is caused when falling, thereis a high possibility that the ejection pitch and the posture of the bagB may become uneven. By using the forced ejector 6, the belt 61 isallowed to contact with the bag B so that the bag B, together with thebelt 61, can be forcibly moved through the turn of the driver roller 62,thereby preventing the variation of the pitch and the posture of the bagas shown in FIG. 4.

In the vertical bag form-fill-seal packaging machine 1, the belt 61 isprovided in a slanted manner instead of vertically, to ensure that thebag B separated from the tubular film Fmc contacts the belt 61. Also,the incline of the belt 61 is such that the bag B moves diagonallydownward, thus reducing the impact that may be caused when the bag Bcontacts with the belt 61, as well as minimizing the change in theposture of the bag B. This also reduces the problem that the bag B maybe transferred in a stand-up posture. As shown in FIG. 6, the incline ofthe belt 61 also contributes to a reduction in the impact that may becaused when the bag B moves from the belt 61 to the transfer conveyor130.

Referring now to FIG. 5 in the vertical bag form-fill-seal packagingmachine 1, the control unit 20 takes control of linking the bag-formingcapacity of the bag-forming/packaging section 5 with the ejection(traveling) speed of the bag B by the forced ejector 6, thereby enablingthe pitch and the ejection time interval of the bag B ejected by theforced ejector 6 onto the transfer conveyor 130 in the downstreamprocess to be set to predetermined values. Even with the bag-formingcapacity varied between low speed (low throughput) and high speed (highthroughput), the pitch between the bags B to be ejected and the ejectiontime interval between the bags B can be adjusted to suit the externaldevices of the downstream processes such as the weight checker 140, thesealing checker 150, and the boxing unit 180 by controlling the servomotor 64 for the forced ejector 6 to change the ejecting speed of thebag B.

In the vertical bag form-fill-seal packaging machine 1 in accordancewith the first embodiment of the present invention, the AC servo motor131 is employed as a driving power source for the transfer conveyor 130,to control the transferring speed of the transfer conveyor 130 accordingto the ejecting speed (traveling speed) and the ejection time intervalfor the bag B at the forced ejector 6. Therefore, even in high-speedforming of the bag B with an improved capacity of the vertical bagform-fill-seal packaging machine 1, the transfer of the bag B from thebag-forming/packaging section 5 to the forced ejector 6 and from theforced ejector 6 to the transfer conveyor 130 become smooth bysynchronizing the ejecting speed of the forced ejector 6 and thetransfer conveyor 130 to aforesaid speeds, thus preventing thedeterioration of the posture and the pitch of the bag B.

The control unit 20 of the vertical bag form-fill-seal packaging machine1 controls the transfer speed of the transfer conveyor 130 according tothe ejecting speed of the forced ejector 6. The control unit 20 alsoprovides data such as the ejecting speed, the ejection time interval,ejection pitch (interval between the bag tops or the bags themselves,bag length, and the like) at the forced ejector 6 to the externalequipment in the downstream process via the external output terminal121. This enables process control at the external equipment (at a devicein the downstream process) such as the weight checker 140, the sealingchecker 150, and boxing unit 180 that takes advantage of aforesaid data.

For example, the external equipment that has received the data on theejection time interval and the ejection pitch (bag-to-bag distance) setsthe processing speed and the transferring speed according to theejection time interval; if the ejection pitch is too small, thetransferring speed is increased so that the bag-to-bag interval isincreased. The ejecting speed can be obtained from the followingformula:(Bag length+bag-to-bag distance)/(ejection time interval).The bag-to-bag distance can be obtained from the following formula:(Ejecting speed)×(ejection time interval)−(bag length).The external equipment can be controlled properly for processing withthe data on (ejection time interval); (bag length); and (ejecting speed)or (bag-to-bag distance).Some variations of the first embodiment are described below as examples.

(1) In the aforesaid embodiment, the forced ejector 6 including the belt61, the driver roller 62, driven roller 63, and the servo motor 64 isincorporated in the vertical bag form-fill-seal packaging machine 1. Theejector may be provided as a device independent from the vertical bagform-fill-seal packaging machine. In such a case, the forced ejector 6including the belt 61, the driver roller 62, driven roller 63, and theservo motor 64 should be provided beneath the vertical bagform-fill-seal packaging machine. In this way, the forced ejector can beretrofitted to a conventional vertical bag form-fill-seal packagingmachine after the removal of the stationary chute.

(2) In the first embodiment described so far, the forced ejector 6includes the belt 61 that contacts the bag B and the driver roller 62 orthe like that lets the belt 61 travel. It is also possible to use amechanism for forcibly feeding the bag B without touching the bag B tomake the forced ejector 6. For example, a vacuuming mechanism forsucking to draw the bag B separated by the transverse sealing mechanism17 may be provided below the transverse sealing mechanism 17. It is alsopossible to provide a mechanism for generating an air flow around thebag B to be separated.

(3) In the aforesaid first embodiment, the transferring speed of thetransfer conveyor 130 is linked with the vertical bag form-fill-sealpackaging machine 1 by utilizing the external output terminal 21 of thecontrol unit 20. The transfer conveyor 130 may also be incorporated intothe vertical bag form-fill-seal packaging machine 1 for the purpose ofcontrolling the transferring speed and ejection time interval in thesame manner of handling as do the bag-forming/packaging section 5 andthe forced ejector 6.

(4) On the belt 61 and the belt for the transfer conveyor 130 of theaforesaid first embodiment, a guide bar may be provided so that only oneof the bags B fits in each space created by the guide bar. By providingsuch a guide bar at an appropriate interval on the belt, the uniformityof the ejection interval between the bags B increases. It is preferableto provide the guide bar so that it is orthogonal to the direction ofthe belt transfer, to prevent the positional shifting of the bag B onthe belt.

(5) As the belt 61 and the belt for the transfer conveyor 130 of theaforesaid first embodiment, a plurality of round belts or a vacuumsuction belt also may be employed.

Second Embodiment

Referring mainly to FIG. 7, vertical bag form-fill-seal packagingmachine, in accordance with a second embodiment of the presentinvention, is a machine for packing a product such as food (potato chipsin this case) into bags. The machine mainly includes abag-forming/packaging section, film supply unit, a forced ejector 206,and a cooling section 9. The structure of the film supply unit and thebag-forming/packaging section are the same as those in the firstembodiment. The bag-forming/packaging section is a main region forpacking the product into bags, a film supply unit 4 supplies thebag-forming/packaging section with the film that ultimately becomesbags. The forced ejector 206 forcibly ejects downward the bags formed bythe bag-forming/packaging section. The cooling section 9 forcibly coolsthe bags formed by the bag-forming/packaging section. An operationswitch, a liquid-crystal display, and a control unit are also providedin the same manner as in the first embodiment of the present invention.

Structure of the Forced Ejector

As shown in FIG. 7, the forced ejector 206 mainly includes endless belts261 a &261 b, driver rollers 262 a & 262 b, driven rollers 263 a & 263b, and an AC servo motor. The servo motor for turning the driver rollers262 a & 262 b is a motor capable of providing extremely fine turningcontrol, and is controlled by the control unit (not shown). The belt 261a is placed on one driver roller 262 a and three driven rollers 263 a sothat it travels in a manner to move the bag B downward according to therotation of the driver roller 262 a. The belt 261 b is placed on onedriver roller 262 b and three driven rollers 263 b so that it travels ina manner to move the bag B downward according to the rotation of thedriver roller 262 b.

As shown in FIG. 8, the belt 261 b is provided with openings 269 at auniform interval to prevent its interference with the sealing jaws 17 a.Also, the driver roller 262 b and the driven rollers 263 b are providedso that they are placed underneath the both ends of the belts 261 b toprevent their interference with the sealing jaws 17 a as seen in FIG. 7.The belt 261 a is similarly constructed. As seen in FIG. 7, the belt 261b extends downward farther than the belt 261 a, to assist in the loadingof the bag B onto the transfer conveyor 130.

A part of the transfer passage formed between the belts 261 a & 261 bmay be inclined between the vertical area and the horizontal area sothat the direction for transferring the bag B changes from vertical tohorizontal as the bag moves through the passage. The rotation of thedriver rollers 262 a & 262 b is controlled so that the belts 261 a &261b travel at a constant speed.

Structure of the Cooling Section

The cooling section 9, which includes two air sprayers 9 a, is providedinside the loops of the endless belts 261 a & 261 b to spray air throughthe opening in the belts 261 a & 261 b to the bag B that is fed downwardby the belts 261 a & 261 b. The ON/OFF switching and the spraying volumeof the air sprayers 9 a are maintained by the control unit.

Operation of the Vertical Bag Form-Fill-Seal Packaging Machine

An operation of the vertical bag form-fill-seal packaging machine inaccordance with the second embodiment is described below.

As with the first embodiment, the sheet-like film fed from the filmsupply unit to the forming mechanism moves through the former and iswound on tube. The sheet-like film is shaped in a tubular form andtransferred, in this condition, downward by being carried on thepull-down belt mechanism. When wound on the tube, the film has both endsoverlapped on its circumference, and the overlapped part is to bevertically sealed by the vertical sealing mechanism.

The tubular film Fmc, now in a cylindrical form as a result of thevertical sealing, moves out of the tube and down to the transversesealing mechanism. At this point, concurrently with the travel of thetubular film Fmc, a mass of items, for example potato chips falls fromthe measuring unit via the tube. Now, through the transverse sealingmechanism, the bottom and the top of the bag are transversely sealed insequence, with the items, for example potato chips present in thetubular film Fmc.

As seen in FIG. 7, in the process of transverse sealing by thetransverse sealing mechanism 17, the cutting process by the cutterprovided in the sealing jaws 17 a is carried out concurrently. Thecutter cuts the approximate center of the transversely sealed part.Also, prior to the process of transverse sealing, the bag B (yet to betransversely sealed) is held by the belts 261 a & 261 b that come intocontact with the bag on both sides, and forcibly fed downward. Thefeeding speed is controlled by the control unit to be synchronous withthe feeding speed on the pull-down belt mechanism and the travelingspeed of the sealing jaws 17 a.

The bag B that has moved out of the transverse sealing mechanism 17 issubjected to the air sprayed from the cooling section 9 while it is heldby the belts 261 a & 261 b of the forced ejector 206 in a sandwichedmanner and being transferred downward. This cools the heat-sealed part,thus increasing its bonding strength before the bag B is loaded on thetransfer conveyor 130.

As shown in FIG. 7, the bag B that has moved out of the cooling section9 leaves the belts 261 a & 261 b and is loaded on the transfer conveyor130 and carried thereon to devices such as the weight checker in adownstream process.

The vertical bag form-fill-seal packaging machine in accordance with thesecond embodiment, of the present invention has the following features:

By turning the belts 261 a & 261 b through the driver rollers 262 a &262 b to move the bag B downward while holding the bag B with the twobelts 261 a & 261 b of the forced ejector 206 in a sandwiched manner,the bag B is forcibly moved to the transfer conveyor 130 in the secondembodiment. Thus, by holding the bag B with the two belts 261 a & 261 bin a sandwiched manner, problems such as slippage of the belts 261 a &261 b resulting in a variation of the pitch of the bags B to be ejectedcan be reduced.

Taking advantage of the structure for holding bag B with the two belts261 a & 261 b in a sandwiched manner, cooling air is sprayed upon bag Bthus held to ensure the bonding strength of the heat-sealed part of theformed bag B.

In a conventional machine, the sealed part (particularly thetransversely sealed part) of the bag B may be sent to the device in adownstream process without sufficiently being cooled down, or air isblown on the bag B on a transfer conveyor with a cooling fan. However,in blowing wind upon the bag B on the transfer conveyor, there is a needto restrict the air volume so that the position of the bag B will not beshifted, which makes it difficult to achieve a sufficient cooling effectin a high-speed operation.

To counter this problem, the second embodiment achieves a condition inwhich the posture hardly will be affected, even with air-spray cooling,through the method of holding the bag B with the two belts 261 a & 261 bin a sandwiched manner. It employs a structure in which air is sprayedwith the air sprayer 9 a to the bag held by the belts 261 a & 261 b in asandwiched manner. This allows effective cooling of the heat-sealed partof the formed bag B, thus reducing bag breakage even with high-speedejection of the bag B.

Some variations of the second embodiment are described below asexamples.

(1) In the aforesaid second embodiment, the bag B that has left thebelts 261 a & 261 b moves almost vertically until it hits against thetransfer conveyor 130 as shown in FIG. 7. In a high-speed operation, theimpact caused when the bag B comes up against the transfer conveyor 130may be great. To reduce the impact, a forced ejector 306 as shown inFIG. 9 may be employed instead of the forced ejector 206.

The forced ejector 306 shown in FIG. 9 includes endless belts 361 a &361 b, driver rollers 362 a & 362 b, driven rollers 363 a & 363 b, adirection-changing driven roller 364, and an AC servo motor. The servomotor for turning the driver rollers 362 a & 362 b provides extremelyfine turning control, and is controlled by a control unit. The belt 361a is placed on one driver roller 362 a and three driven rollers 363 a sothat it travels in a manner to move the bag B downward according to therotation of the driver roller 362 a. The belt 361 b is placed on onedriver roller 362 b, three driven rollers 363 b, and thedirection-changing driven roller 364 so that it travels in a manner tomove the bag B downward according to the rotation of the driver roller362 b.

The belts 361 a & 361 b are provided with openings at a uniform intervalto prevent its interference with the sealing jaws 17 a. The driverrollers 362 a & 362 b, the driven rollers 363 a & 363 b, and thedirection-changing driven roller 364 are provided so that they comeunder the both ends of the belts 361 a & 361 b to prevent theirinterference with the sealing jaws 17 a. The rollers 362 a, 362 b, 363a, 363 b, & 364 are provided in the positions shown in FIG. 9, so thatthe bag B, after leaving the cooling section 9, moves in a differentdirection, changing from vertical to horizontal, toward the transferconveyor 130. The rotation of the driver rollers 362 a & 362 b iscontrolled so that the belts 361 a & 361 b travel at a constant speed.Thus, the structure of the forced ejector 306 in the second embodimentis made to allow, in its lower portion, the bag B to move toward thehorizontal direction; i.e. the surface on which the bag B below the belt361 b comes into contact is inclined so that the bag is ejectedhorizontally onto the transfer conveyor 130. This significantly reducesthe impact that may be caused when the bag B is loaded onto the transferconveyor 130

(2) Referring to FIG. 7, the forced ejector 206 in the second embodimentmay further be provided with a function to optimize the volume of thegas to be filled in the bag B. In such a case, the distance between thebelts 261 a & 261 b of the forced ejector 206 is made variable by ameans for changing the belt-to-belt distance. The distance between thebelts 261 a & 261 b is also controlled by the control unit 20 accordingto the type of the bag B and the volume of the gas required to fill thebag.

A possible example of the means for changing the belt-to-belt distanceis a mechanism that moves a first unit having the belt 261 a, the driverroller 262 a, and the driven roller 263 a, and a second unit having thebelt 261 b, the driver roller 262 b, and the driven roller 263 b to theright or left by using motorized ball screws and a servo motor. As shownin FIG. 10, this makes it possible to shift each element of the forcedejector 206 from the position shown with the solid line to the positionshown with the broken line, and to change the distance between the belts261 a & 261 b into any value with the control unit. Then, by adjustingthe distance between the belts 261 a & 261 b while setting the volume ofthe gas to be filled which is sprayed from above the tubular film Fmcsomewhat higher, the volume of the gas to be filled in the bag B, or thevolume of the bag B, is made uniform.

In a conventional machine, the volume of the gas to be filled isadjusted by varying the period of the spraying time, for example.However, if the gas supply sources are centralized in a large-scaleplant, the supply pressure of the gas supply source often varies, thusmaking it difficult to prevent variation in the volume of gas to befilled. A variation in the volume of gas to be filled results in avariation in the volume of the bag B, leading to a problem at the boxingunit in a downstream process. The boxing unit packs a specified numberof the bags B into carton boxes by the use of a handling mechanism thatutilizes suction or the like. If the volume of the bag B is not constantas described above, the following problems may occur: mishandling, bagbreakage, a gap in the carton box after the specified number of the bagsB are placed inside. Thus problems during transportation, and a failureto pack the specified number of the bags B in the carton box may result.

To counter the above, this variation of the second embodiment, by takingadvantage of structures for holding the bag B with the two belts 261 a &261 b in a sandwiched manner and by adjusting the distance between thetwo belts 261 a & 261 b, enables the controlling of the volume of thegas to be filled in the formed bag B, thus achieving uniformity of thevolume of the bag B. This allows the bag B, almost uniform in volume, tobe supplied to the devices in a downstream process, which should reducethe incidence of problems in the devices during the downstream process.

The terms of degree such as “substantially”, “about” and “approximately”as used herein mean a reasonable amount of deviation of the modifiedterm such that the end result is not significantly changed. These termsshould be construed as including a deviation of at least ±5% of themodified term if this deviation would not negate the meaning of the wordit modifies.

While only selected embodiments have been chosen to illustrate thepresent invention, it will be apparent to those skilled in the art fromthis disclosure that various changes and modifications can be madeherein without departing from the scope of the invention as defined inthe appended claims. Furthermore, the foregoing description of theembodiments according to the present invention are provided forillustration only, and not for the purpose of limiting the invention asdefined by the appended claims and their equivalents.

1. A method of forming a plurality of bags with items filled therein andtransferring the bags to an external device, comprising steps of:forming bags from a film while filling the bags with items; severingeach of the bags; ejecting the severed bags one by one onto a firsttransfer unit; carrying the bags diagonally downward with the firsttransfer unit, a speed at which the first transfer unit carries the bagsbeing controlled to be faster as an ejection interval at which the firsttransfer unit receives the severed bags becomes shorter; ejecting thebags from the first transfer unit onto a second transfer unit; carryingthe bags with the second transfer unit in a direction not parallel tothe direction in which the first transfer unit carries the bags; andejecting the bags from the second transfer unit onto the externaldevice, ejection intervals at which the second transfer unit ejects thebags onto the external device being substantially even.
 2. The method asdefined in claim 1, wherein during the ejection of the bags from thefirst transfer unit to the second transfer unit, a posture of the bagsis controlled.
 3. The method as defined in claim 1, wherein the firsttransfer unit is a belt.
 4. The method as defined in claim 3, whereinthe belt is inclined so that the bags move diagonally downward.
 5. Themethod as defined in claim 1, wherein in the carrying of the bags by thefirst transfer unit, the speed of the first transfer unit is controlledaccording to control settings stored in a memory storage unit.
 6. Themethod as defined in claim 1, wherein in the ejection of the bags fromthe first transfer unit, an ejection interval of the first transfer unitis controlled according to control settings stored in a memory storageunit.
 7. The method as defined in claim 1, wherein the forming of thebags includes forming the film into a tubular shape, transferring thetubular-shaped film downward, vertically sealing an overlapped part ofthe tubular-shaped film, transversely sealing the tubular-shaped film toform the bags, and severing and ejecting each of the bags.
 8. The methodas defined in claim 7, wherein the sealing is by heat-sealing.
 9. Themethod as defined in claim 1, wherein in the ejection of the bags ontothe first transfer unit, the severed bags are dropped onto the firsttransfer unit and the bags do not contact the first transfer unit untilafter the bags are severed.
 10. The method as defined in claim 1,wherein in the ejecting of the bags from the first transfer unit, aspeed at which the bags are ejected from the first transfer unit ontothe second transfer unit is no faster than a speed at which the bags areejected onto the first transfer unit.
 11. A method of forming aplurality of bags with items filled therein and transferring the bags toan external device, comprising steps of: forming bags from a film whilefilling the bags with items; severing each of the bags; ejecting thesevered bags one by one onto a first transfer unit, the first transferunit including a pair of belts; carrying the bags downward with thefirst transfer unit while sandwiching the bags with the pair of belts, aspeed at which the first transfer unit carries the bags being controlledto be faster as an ejection interval at which the first transfer unitreceives the severed bags becomes shorter; ejecting the bags from thefirst transfer unit onto a second transfer unit; carrying the bags withthe second transfer unit in a direction not parallel to the direction inwhich the first transfer unit carries the bags; and ejecting the bagsfrom the second transfer unit onto the external device, ejectionintervals at which the second transfer unit ejects the bags onto theexternal device being substantially even.
 12. The method as defined inclaim 11 wherein during the ejection of the bags from the first transferunit onto the second transfer unit, a posture of the bags is controlled.13. The method as defined in claim 11, wherein in the carrying of thebags by the first transfer unit, the speed of the first transfer unit iscontrolled according to control settings stored in a memory storageunit.
 14. The method as defined in claim 11, wherein in the ejection ofthe bags by the first transfer unit, an ejection interval of the firsttransfer unit is controlled according to control settings stored in amemory storage unit.
 15. The method as defined in claim 11, wherein theforming of the bags includes forming the film into a tubular shape,transferring the tubular-shaped film downward, vertically sealing anoverlapped part of the tubular-shaped film, transversely sealing thetubular-shaped packaging material to form the bags, and severing andejecting each of the bags.
 16. The method as defined in claim 15,wherein the sealing is by heat-sealing.
 17. The method as defined inclaim 11, wherein in the ejection of the bags onto the first transferunit, the severed bags are dropped onto the first transfer unit and thebags do not contact the first transfer unit until after the bags aresevered.
 18. The method as defined in claim 11, wherein in the ejectingof the bags from the first transfer unit, a speed at which the bags areejected from the first transfer unit onto the second transfer unit is nofaster than a speed at which the bags are ejected onto the firsttransfer unit.
 19. The method as defined in claim 11, wherein in thecarrying of the bags by the first transfer unit, a part of a transferpassage formed between the pair of belts of the first transfer unit isinclined so that a direction in which the bags are transferred changesas the bags move through the transfer passage.
 20. The method as definedin claim 11, wherein a distance between the pair of belts is adjustableaccording to a type of the bags.